This invention relates to a detector, and in particular to a fire detector.
A fire detector typically includes one or more sensing elements, such as an optical smoke sensing element, a CO sensor for detecting carbon monoxide, or a pyroelectric sensor for detecting the presence of a flame. The problem with known fire detectors is that each type of sensing element tends to decay with time, without there being provided means for accurately establishing exactly how much the sensitivity of its sensing element has changed since installation. This problem is exacerbated where a fire detector is provided with two or more different types of sensor (for example an optical smoke detecting sensor and a CO sensor), which tend to decay at different rates, requiring more frequent manual inspection which is time consuming and expensive.
This problem can be overcome in cases where a fire detector sensor is associated with an EEPROM, in which case a manufacturing date code is entered into the EEPROM. This manufacturing date code can then be interrogated by control and indicating equipment (CIE) which is provided to monitor and control the fire detector. For cost reasons, however, many fire detectors do not have EEPROMs associated with their sensors. Throughout this specification, the term “date code” should be taken to mean a code representation of the period of time during which a particular sensor was manufactured. Typically, this period of time will be six months or one year.